275 research outputs found
Zooplankton community structure in the Yellow Sea and East China Sea in autumn
Study on zooplankton spatial distribution is essential for understanding food web dynamics in marine ecosystems and fishery management. Here we elucidated the composition and distribution of large mesozooplankton on the continental shelf of the Yellow Sea and East China Sea, and explored the zooplankton community structure in these water masses. Sixty vertical hauls (bottom or 200 m in deep water to surface) using a ring net (diameter 0.8 m, 505-μm mesh) were exploited in November 2007. The biogeographic patterns of zooplankton communities were investigated using multivariate analysis methods; copepod biodiversity was analyzed using univariate indices. Copepods and protozoans were dominate in the communities. Based on the species composition, we divided the study areas into six station groups. Significant differences in zooplankton assemblages were detected between the Yellow Sea and East China Sea. Species richness was higher in East China Sea groups than those in Yellow Sea, whereas taxonomic distinctness was higher in Yellow Sea than in East China Sea. There was a clear relationship between the species composition and water mass group.O estudo da distribuição espacial do zooplancton é essencial para o entendimento não só da dinâmica das teias tróficas nos ecossistemas marinhos, mas também para o manejo da pesca. Neste trabalho procuramos elucidar a composição e distribuição do mesozooplancton na plataforma continental do Mar Amarelo e do Mar da China Oriental, e explorar a estruturas das comunidades nessas duas massas de água. Sessenta arrastos verticais (do fundo ou de 200m até a superfície) foram realizados em Novembro de 2007, usando uma rede circular com diâmetro de 0,8m e malhagem de 505μm. Os padrões biogeográficos das comunidades do zooplancton foram investigados, utilizando-se métodos de análise multivariada. A biodiversidade de Copepoda foi analisada através de indices univariados. Copéodes e protozoários foram os organismos dominantes nas amostragens. Baseados na composição de espécies, pudemos dividir a área de estudo em seis grupos de estações. Diferenças significantes nas assembléias de zooplancton foram detectadas entre o Mar Amarelo e o Mar da China Oriental. A riqueza de espécies foi mais elevada nesta última área, enquanto a distinção taxonômica foi mais alta no Mar Amarelo. Houve uma clara relação entre composição de espécies e tipo de massa de água
Do Loyal Customers Pay More in Live Streaming?
With the rise of the live streaming industry, streamers are facing stiff competition. While there is a common perception that loyalty generates more profits for the firm, there is also conflicting evidence that loyal customers may not be charged more. The live streaming context provides an ideal setting to empirically examine the value of loyal customers and offers a new dimension for measuring behavioral loyalty. Our results suggest that customers with higher consumption loyalty generally pay less while those with higher social loyalty tend to voluntarily pay more. Moreover, there is a crowding-out effect for the same type of resources and a compensation effect between different types of resources concerning the relationship between historical and current inputs. Theoretical explanations drawn on the social exchange theory and practical implications are discussed
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Dorsal root ganglion macrophages contribute to both the initiation and persistence of neuropathic pain.
Paralleling the activation of dorsal horn microglia after peripheral nerve injury is a significant expansion and proliferation of macrophages around injured sensory neurons in dorsal root ganglia (DRG). Here we demonstrate a critical contribution of DRG macrophages, but not those at the nerve injury site, to both the initiation and maintenance of the mechanical hypersensitivity that characterizes the neuropathic pain phenotype. In contrast to the reported sexual dimorphism in the microglial contribution to neuropathic pain, depletion of DRG macrophages reduces nerve injury-induced mechanical hypersensitivity and expansion of DRG macrophages in both male and female mice. However, fewer macrophages are induced in the female mice and deletion of colony-stimulating factor 1 from sensory neurons, which prevents nerve injury-induced microglial activation and proliferation, only reduces macrophage expansion in male mice. Finally, we demonstrate molecular cross-talk between axotomized sensory neurons and macrophages, revealing potential peripheral DRG targets for neuropathic pain management
Identification of microRNAs Actively Involved in Fatty Acid Biosynthesis in Developing Brassica napus Seeds Using High-Throughput Sequencing
Seed development has a critical role during the spermatophyte life cycle. In Brassica napus, a major oil crop, fatty acids are synthesized and stored in specific tissues during embryogenesis, and understanding the molecular mechanism underlying fatty acid biosynthesis during seed development is an important research goal. In this study, we constructed three small RNA libraries from early seeds at 14, 21 and 28 days after flowering (DAF) and used high-throughput sequencing to examine microRNA (miRNA) expression. A total of 85 known miRNAs from 30 families and 1,160 novel miRNAs were identified, of which 24, including 5 known and 19 novel miRNAs, were found to be involved in fatty acid biosynthesis. bna-miR156b, bna-miR156c, bna-miR156g, novel_mir_1706, novel_mir_1407, novel_mir_173, and novel_mir_104 were significantly down-regulated at 21 DAF and 28 DAF, whereas bna-miR159, novel_mir_1081, novel_mir_19 and novel_mir_555 were significantly up-regulated. In addition, we found that some miRNAs regulate functional genes that are directly involved in fatty acid biosynthesis and that other miRNAs regulate the process of fatty acid biosynthesis by acting on a large number of transcription factors. The miRNAs and their corresponding predicted targets were partially validated by quantitative RT-PCR. Our data suggest that diverse and complex miRNAs are involved in the seed development process and that miRNAs play important roles in fatty acid biosynthesis during seed development
Wireless Carriers’ Exclusive Handset Arrangements: An Empirical Look at the iPhone
Since the Apple iPhone’s first launch in 2007 with an exclusive
arrangement with AT&T, it has garnered overwhelmingly positive
responses from consumers and from the media. With its success, exclusive
contracts between handset makers and wireless carriers have come under
increasing scrutiny by regulators and lawmakers. Such practices have
been criticized by regulators, by the media, and by
“locked-out” consumers, due to the fact that a consumer has
to subscribe to a particular service provider if he or she strongly
prefers one handset to others. In this paper, we empirically examine the
impact of handset exclusivity arrangements on consumer welfare. First we
study consumers’ purchase decisions in mobile services that
include the choice of a handset and of a service provider. We do so by
combining survey data on consumers’ purchase decisions with
supplemented data on prices and features of common handsets. Next,
assuming a Stackelberg leader-follower relationship between the handset
manufacturers and the service providers, and using our demand estimates,
we recover the marginal costs for the players in the market. We then
simulate what would have happened in the counterfactual scenario when
the iPhone is available from all carriers. Our results suggest that, if
we take into account price adjustments from handset manufacturers and
service providers in response to the change in market structure,
consumer welfare will increase by $326 million without the exclusive
arrangement. We view our analysis as a starting point to a more complete
characterization of consumer behavior and the complex relationships
among players in this industry
Evaluation of brain default network fMRI of Insomnia with Depression patients at Resting state
Abstract: Research Purpose: By conducting fMRI research on insomniacs with depression in resting state, this experiment reveals the abnormality in the patient's DMN and its neural pathogenesis, and different degrees of depression's impact on the neural networks causing weakened cognitive function. Consequently, it offers objective imageological basis for clinical cognitive impairment treatment and evaluation of such treatment. Method: a group of 40 cases are selected as the insomniac group, consisting of 20 as mild depression group and 20 as moderate depression group. And another 40 cases are selected as the HC group. All the testees take PSQI, HAMD, 3.0T routine MRI examination and fMRI, and cases with abnormal brain structures are excluded. Then on the basis of PCC as the seed point, comparisons are made between the insomniac group and HC group, between mild and moderate depression group in terms of their DMN differences. Result: Depressive Insomniac Group have stronger functional connection with PCC/pC: bilateral superior frontal gyri and bilateral middle cingulate gyri; the following regions have weaker functional connection: left occipital lobe lingual gyrus/ parahippocampal gyrus/ fusiform gyrus, right superior temporal gyrus/temporal pole, right middle temporal gyrus/middle occipital gyrus, and left occipital lobe/middle temporal gyrus. Compared with Mildly Depressive Group, the following encephalic regions of Moderately Depressive Insomniac Group have stronger functional connection with PCC/pC: right middle cingulate cortex and right frontal gyrus; the following regions have weaker functional connection: left parahippocampal gyrus. Conclusion: There is abnormity in the brain default mode network of insomniacs with depressive symptoms. The depression degree of insomniacs varies. There are differences in the brain default mode network. It is suggested that there is a positive correlation between the middle cingulate gyrus and insomnia and depression, this is also shown between the activated degree of the middle frontal gyrus and insomnia and depression. There is a negative correlation between the activated degree of the parahippocampal gyrus and insomnia and depression. This research also suggested that there is a cognitive disorder and a neutral network mechanism of emotion regulation disorder among depressive insomniacs
Identification of Key Gene Networks Associated With Cell Wall Components Leading to Flesh Firmness in Watermelon
Flesh firmness of watermelon is an important quality trait for commercial fruit values, including fruit storability, transportability, and shelf life. To date, knowledge of the gene networks underlying this trait is still limited. Herein, we used weighted genes co-expression network analysis (WGCNA) based on correlation and the association of phenotypic data (cell wall contents) with significantly differentially expressed genes between two materials, a near isogeneic line “HWF” (with high average flesh firmness) and inbred line “203Z” (with low average flesh firmness), to identify the gene networks responsible for changes in fruit flesh firmness. We identified three gene modules harboring 354 genes; these gene modules demonstrated significant correlation with water-soluble pectin, cellulose, hemicellulose, and protopectin. Based on intramodular significance, eight genes involved in cell wall biosynthesis and ethylene pathway are identified as hub genes within these modules. Among these genes, two genes, Cla012351 (Cellulose synthase) and Cla004251 (Pectinesterase), were significantly correlated with cellulose (r2 = 0.83) and protopectin (r2 = 0.81); three genes, Cla004120 (ERF1), Cla009966 (Cellulose synthase), and Cla006648 (Galactosyltransferase), had a significant correlation with water-soluble pectin (r2 = 0.91), cellulose (r2 = 0.9), and protopectin (r2 = 0.92); and three genes, Cla007092 (ERF2a), Cla004119 (probable glycosyltransferase), and Cla018816 (Xyloglucan endotransglucosylase/hydrolase), were correlated with hemicellulose (r2 = 0.85), cellulose (r2 = 0.8), and protopectin (r2 = 0.8). This study generated important insights of biosynthesis of a cell wall structure and ethylene signaling transduction pathway, the mechanism controlling the flesh firmness changes in watermelon, which provide a significant source to accelerate future functional analysis in watermelon to facilitate crop improvement
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